When putting a new unit into operation, the suction strainers should be cleaned after a few hours of operation. Refrigerants have a solvent action and will loosen any foreign matter in the system. This foreign matter will eventually reach the suction strainers and after a few days of operation, the strainers will need cleaning. Strainers should be inspected frequently during the first few weeks of plant operation, and then cleaned as found necessary.

The suction strainers are located either in the compressor housing or in the suction piping. The procedure for cleaning a strainer is as follows:

1. Pump down the compressor.

2. Slowly bleed pressure from unit.

3. Remove the strainer and inspect it for foreign matter.

4. Clean the strainer screen by dipping it in an approved solvent and then allow it to dry.

5. Replace the strainer and evacuate the air from the compressor.

6. Test the housing for leaks by wiping up all oil and then using a halide leak detector.

CONDENSERS

The compressor discharge line terminates at the refrigerant condenser. In shipboard R-12 installations, these condensers are usually of the multipass shell-and-tube type, with water circulating through the tubes. The tubes are expanded into grooved holes in the tube sheet so as to make an absolutely tight joint between the shell and the circulating water. Refrigerant vapor is admitted to the shell, and condenses on the outer surfaces of the tubes.

Any air or noncondensable gases which may accidentally enter the refrigeration system is drawn through the piping and eventually discharged into the condenser with the R-12 gas. The air or noncondensable gases accumulated in the condenser are lighter than the refrigerant gas and rise to the top of the condenser when the plant is shut down. A purge valve, for purging the refrigeration system (when necessary), is installed either at the top of the condenser, or at a high point in the compressor discharge line.